Jillian Michaels‘ former partner, Heidi, has filed docs to end the couple’s domestic partnership … months after the celebrity trainer announced the two were going their separate ways.

Heidi filed docs for “dissolution with minor children” in Los Angeles Monday. The couple has a 6-year-old son and 9-year-old daughter together. In a statement in June of last year, Jillian said, “Heidi and I have been split for a while now. We’ve found we’re better friends and parents living apart than staying together.”

We’re told the two never got married … and the docs were to end the couple’s domestic partnership.

Michaels proposed to Heidi in 2016 on the finale of her show, “Just Jillian” … the pair had been together for 9 years when they announced their split.

Michaels found her fame as a trainer on “Biggest Loser” from 2004 to 2006 … she returned to the show after a brief hiatus in 2007.